Adaptive methods for sustaining groundwater regime techniques adopted for artificial recharge

There are several important techniques (Athavale 2003; Sharma 1998) used for artificial recharge as described below.

In the water spreading technique, surface water from perennial rivers/streams is allowed to spread over a large area for a sufficiently long period so that it percolates to recharge the aquifers.

With recharge basin and percolation tanks/ ponds, the concept is to maximize the contact area and time of surface water with soil so that surface water percolates down to recharge groundwater. The technique involves construction of small dams or weirs across the river course. Monsoon streams run for short periods because of the limited period of rainfall. Alternatively the flow of the streams is restricted due to check dams, weirs and gully plugs, enabling more contact time for flowing water to infiltrate into the ground rather than go as surface runoff.

Surplus surface water, after treatment, can be artificially recharged through injection wells which have a similar construction to a tube well, but with a purpose of recharging the deep semi-confined aquifer. The same wells can be used to retrieve water during period of droughts and thus are useful for the changing climate.

Artificial recharge can be induced into ground-water, with deliberate creation of a cone of depression along rivers and streams. During flow time the stream can be effectively recharging groundwater which can be utilized during drought periods.

Another important groundwater management practice that is emerging is the identification of certain deep confined aquifers in regions where droughts occur periodically, and such deep aquifers can be utilized during such calamities. Deep confined renewable or non-renewable aquifers, if available in a region, are the most suitable source of safe and usually good quality water available for drinking or even irrigation. Such aquifers generally have a high residence time which can be determined by 14C dating method (Vrba & Verhagen 2006).

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